using System;
class Teste
{
	static void Troca(ref string s, ref string t)
	{
		string tmp = s; s = t; t = tmp;
	}

	static void Main()
	{
		string a = "Passo", b = "Coelho";
		Console.WriteLine(a+b);
		Troca(ref a, ref b);
		Console.WriteLine(a + b);
	}
}